side arm or plate heat exchanger, which is better

[geobckmstr]

So my hot water heater went out, was about 20 years old so it was expected. My outdoor boiler is about 9 years old when i hooked up the side arm exchanger. When taking the old WHeater out i was surprised how the gaskets on the fittings all broke apart. the heat of the boiler up up 180 was to much for the "watts and shark fittings. Looking at new hot water heaters the drain valves are all plastic.?? so what to do? Go with a plate heat exchanger?? THANKS IN ADVANCE.

 

[ChoppyChoppy]

Are you saying the water in your water heater was 180*?! That is WAY too hot, for the water heater, and more so for users. 120-140* is where is should be.

Put a zone valve on the water heater coil and it only comes on when calling for heat. That's how mine is setup.

 

[Nick Kent]

Do you have an indirect hot water tank? Get a stainless tank with a coil inside it. It is fine to run the tank to 180 degrees. Just put a mixing valve on the discharge side. I have solar hot water, and the sun will take it to 180 if it can. Then mixes on the way out to 120. As long as you aren't burning extra wood to get your tank to 180 that is a good setup.

 

[ChoppyChoppy]

Heat come from a nautral gas boiler, but heated water is heated water.

 

[ChoppyChoppy]

Hmm, I just replied before about 180* water being way too hot. Where did that post go?

 

[Sandhill Crane]

Hmm, I just replied before about 180* water being way too hot. Where did that post go?

Post # 2: I still see it.

 

[geobckmstr]

I have a mixing valve where it leaves the tank and enters the hot water line. Do keep it at 125, but during the winter, if i keep my boiler at 180, there is the possibility of your tank reaching that temp. if you are not using hot water.

 

[NSMaple1]

Define 'better'.

Sidearm is 'better' re. it works very simply by convection and needs no other pumps. Flat plate is 'better' re. it recovers more heat than a sidearm per unit of supply water.

If you only use it in the winter when you have lots of hot supply water I would likely stick to a sidearm. That's what I started with, but added a flat plate to it because the sidearm wouldn't heat enough when heating from storage when not heating the house & the storage temps got down to what still should have been useable but wasn't because the sidearm wouldn't get enough heat out of it.

I would get rid of the plastic drain valve & T in the bottom sidearm fitting at that tapping, then add a metal drain valve there. You could also add controls that would limit how hot it gets - if you want. A Johnson A419 and a zone valve should do it.

What fittings had gaskets? I don't have any, anywhere in my system. Except for at circulator flanges, and they can get pretty hot at times but I've had no issues ever with those, in the 20+ years we've been here.

 

[ChoppyChoppy]

Post # 2: I still see it.

Weird it loads on my computer at the shop but not on my phone. huh!

 

[cantoo]

Just a little FYI. Several years ago we shut down the owb in the spring, flipped the breaker back on for the electric heater and then a week later we ran out of hot water. Turns out the hot water heater wouldn't work anymore. Figured the coils were done as it's not that old. Sidearm was in the way of replacing the heater coils so being a puter off guy I just relite the owb and didn't worry about it. This year my lovely wife decided we are shutting down the owb for the summer, she buys new coils and the hen picked husband I am I changed them. Got everything wired up and went to check the coil wires for power to make sure things are okay and dang no voltage. Go upstairs to get my glasses and have a little look see. Well the little red rivets that hold the wire plate on actually have RESET in little tiny tiny letters on them. Push them in with a tiny screwdriver and bang we have power. $120 for coils that I didn't even need. I assume that the 180 degree water from the owb tripped the RESETS several years ago. So before you do anything put your glasses on and check for the resets.

 

[NSMaple1]

Just a little FYI. Several years ago we shut down the owb in the spring, flipped the breaker back on for the electric heater and then a week later we ran out of hot water. Turns out the hot water heater wouldn't work anymore. Figured the coils were done as it's not that old. Sidearm was in the way of replacing the heater coils so being a puter off guy I just relite the owb and didn't worry about it. This year my lovely wife decided we are shutting down the owb for the summer, she buys new coils and the hen picked husband I am I changed them. Got everything wired up and went to check the coil wires for power to make sure things are okay and dang no voltage. Go upstairs to get my glasses and have a little look see. Well the little red rivets that hold the wire plate on actually have RESET in little tiny tiny letters on them. Push them in with a tiny screwdriver and bang we have power. $120 for coils that I didn't even need. I assume that the 180 degree water from the owb tripped the RESETS several years ago. So before you do anything put your glasses on and check for the resets.

Good point. I was assuming that when he said the heater was done, he meant it was leaking. But I guess he didn't say.

I have had to reset mine a couple of times. I controlled in an option to let me 'overcharge' my DHW tank temp by 20° if I want to with the flip of a switch, that would let me go longer between fires if I wanted (80 gallon tank). But doing that can trip the reset if I forget to flip the switch back again. I have temp gauges on the tank, I think the trip temp for me is around 160° or just a bit below. If I don't flip the switch my tank usually heats to around 140. First time it happened I was also thinking fried element until I realized about the little red button on the top element stat. Mine is big enough I can reset it by pushing with my finger. Had to push it quite hard before it clicked in.

 

[Guswhit]

I a gas DHW heater a few years ago with a sidearm. 2 issues I had: First, big problem, on the weekends it seemed that more laundry was done and more hot water was used and we could run out. TO remedy that I put a small recirc pump on that I could force water through it to heat faster. It was never a problem anytime except for lots of laundry on the weekend. 2nd issue was, we went away for several days one winter. I had a buddy stop over and keep the OWB going. With no usage, the DHW tank apparently got up to the OWB temp and fried the gas valve. There was some sort of safety mechanism on it that if it ever got over a certain temp it would fry and then not be able to start again. Now that's not really a problem until you want to shut the OWB down and go back to gas. Rather expensive lesson! I'm putting a plate exchanger in after the DHW tank this time.

 

[geobckmstr]

I knew about the reset and had used it numerous times, it needed replacing even thou the majority of its life it was only a hot water holding tank. The gaskets that were fried were the screw connections that were used on the hot water loop i created from the pressure relieve valve and drain. Also used shark fittings that have a rubber seal-gaskets in them, seem to be OK. Just looked like it couldn't take the heat. All the foam insulation was melted to the copper. The funny part is I have a fan and controls and usually keep it at 160 fan off, 140 fan on. very seldom go to 180.